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Birth, like life, is messy. But, while life’s messes often harm health, the untidiness of our entrance into the world may profoundly protect it—at least that’s a leading hypothesis among microbiome researchers.

Microbes picked up from mom while in or exiting the womb kick off humans’ lifelong association with the invisible critters that live in and on us and affect our health. In cases where that microbial colonization of a newborn goes awry, researchers have noted links to chronic health problems, such as asthma, obesity, allergies, and immune deficiencies. Researchers have also found that such a microbial debacle is often brought on by Cesarean delivery (C-section), which is a common surgical procedure to birth a baby through the mother’s abdomen rather than the normal shove down the birth canal.

To reverse the potential ill-fate of C-section babies, researchers smeared surgically delivered babies with the vaginal fluids from their mothers in the moments just after birth. After tracking the babies and their microbiomes for a month, the researchers report Monday in Nature Medicine that the quick slather partly restored normal microbiome development.

The researchers “have taken an important first step toward developing active interventions that may someday enhance the introduction of the newborn to microbial partners and facilitate a lifelong healthy symbiotic relationship,” microbiome researcher Alexander Khoruts of the University of Minnesota, wrote in a commentary on the findings.

For the study, researchers followed 18 babies from birth to one month old. Seven of the babies were born vaginally and 11 were born by C-section. Of those 11 C-section babies, four were rubbed down with vaginal fluids from their mothers. To collect the fluids, researchers placed neatly folded pieces of gauze into the mothers’ vaginas for an hour right before their scheduled C-section. Within the first two minutes after birth, a researcher wiped the microbe-laden gauze over the entirety of the newborn’s body—starting at the lips and smearing to the face, thorax, arms, legs, genitals, anal region, and back.

Then, for the next 30 days, the researcher periodically swabbed the 18 newborns’ mouths, bums, and skin. From the swabs, the researchers analyzed the babies’ microbial communities as they established and evolved.

As in previous data, the researchers noted a clear divergence between the microbial communities on the vaginally delivered babies and those from the un-slathered C-section babies. C-section babies bathed with vaginal fluid, on the other hand, had microbiomes that looked pretty similar to the ones found on the vaginally delivered babies—particularly their skin and oral microbiomes. The anal communities were only partly restored, suggesting their gut microbiomes were still different.

In particular, both vaginally delivered and swabbed C-section babies had early enrichments of Lactobacillus and Bacteroides bacteria, which weren’t seen in unwiped C-section babies.

The data proves that the intervention could alter the babies’ microbiomes. And the researchers are hopeful that further tweaks to the vaginal fluid-smearing could completely mimic the microbial transfer of mother to baby during vaginal delivery.

While promising, the authors cautioned that it’s just an early days proof-of-principle. It’s important to publish this proof-of-principle and make it public now, first author Maria Dominguez-Bello of New York University said, because “it gives credibility,” to the idea. The credibility is sorely needed as she and colleagues compete for grants to do the larger, next-step studies, she said.

Such a long-term study would involve a lot more babies and follow them and their microbiomes for years. The data from such a study could prove that the microbial adjustments from the vaginal swabbing can stick—permanently affecting the microbiome—and, most importantly, improve health.